Automatic slack adjuster



Feb. 22, N38. F. E. SCHWENTLER 2,109,036

AUTOMATIC SLACK ADJUSTER Filed NOV. 10, 1936 2 Sheets-Shedl l Figi INVENTOR \NCIS ESC HWENTLER.

BY l ff/A ATTORNEY Feb. 22, w38., F. E. SCHWENTLER v ZS AUTOMATIC SLACK ADJUSTER Filed Nov. l0, 1936 2 Sheets-Sheet 2 INVENTQR FRANCIS ESCHWENTLER EY l.

ATTORNEY Patented Feb. 22, 1938 ilbli'i'ED ST PAT E AU'li/ATIC SLACK ADJUSTER Application November 10, 1936, Serial No. ll..il0

9 Claims.

This invention relates to automatic slack adjusters for railway brakes and more particularly to that type of slack adjuster disclosed in my pending application, Serial No. 111,222 led November 17, 1936, in which the longitudinal axes of the slack take-up mechanism and the motor for actuating the mechanism are spaced apart and extend parallel with each other.

The principal object of the present invention is to provi-de an automatic slack adjuster of the above mentioned type having a simpliiied driving means from the actuating motor to the slack take-up mechanism.

In the accompanying drawings, Fig. 1 is a vertical longitudinal sectional View of an automatic slack adjuster embodying the invention; Fig. 2

is a cross-sectional View of the same taken on the line 2-2 of Fig. 1, and Fig. 3 is a. fragmentary sectional view taken on the line 3 3 of Fig. 1.

Fig. li is a fragmentary vertical longitudinal sectional view of an automatic slack adjuster embodying a modification of the invention, and

Fig. 5 is a cross-sectional view of the same taken on the line 5 5 of Fig. 4. Fig. 6 is a sectional View similar to Fig. 4 but illustrating another modification of the invention.

As shown in the drawings, the slack adjuster may comprise casing sections i and 2 which may be secured together by bolts 3 or the like.

The casing section l may comprise a horizontally disposed hollow portion Il which, at one end, is provided with an integral laterally extending face plate 5 which is adapted to be secured to any suitable member of a car truck or body or to the usual brake cylinder (not shown) of a iiuid pressure brake equipment, and at the other end is provided with a wall Slidably mounted in the portion 4 of the casing section l so as to be movable back and forth o longitudinally thereof is a non-rotatable crosshead i which is operatively connected, by means of a pin 8, to a horizontally disposed laterally eX- tending brake element 9 to be adjusted, which element may be the dead brake lever of a railway truck brake rigging.

Secure-d to the cross-head l is a non-rotatable slack take-up screw I@ which extends longitudinally of the hollow portion l of the casing section i and through an opening l l in the end wall JO of said casing section, and which at its outer end has screw-threaded connection with a rotatable adjusting nut l2 journalled in the casing section 2 and wall 6 in axial alignment with the screw.

5- :The adjusting nut I2, adjacent its inner end,

(Ci. 18S-293) is provided with a ratchet wheel I3 and to the right of the ratchet wheel is provided with an annular collar It which is adapted to engage with the casing section 2 to prevent undue longitudinal movement of the nut in the direction toward the right hand, undue movement of the nut in the opposite direction being prevented by the engagement ci the inner end of the nut with an annular thrust bearing plate l5 abutting the end wall of the casing section l. 10

The outer end of the adjusting nut l2 project beyond that portion oi' the casing section 2 in which the nut is journalled so as to provide for the engage-ment of the nut by a wrench or other suitable tool when it is desired to reset the ad- 15 just-er as is necessary when worn brake shoes are replaced by new ones.

Arranged below the take-up screw l0 and adjusting nut l2 and slidably mounted in the casing section 2 to move back and forth parallel to the longitudinal axis of the adjusting nut l2 is a piston i6 having a piston rod Il having at its outer end a spring seat I8 which is operatively engaged by one end of an actuating spring i9, the opposite end of the spring being seated on 25 the casing section 2.

The piston rod is provided with a lug 2li which is slidably guided in a groove 2l provided in the casing section 2, the engagement of the lug within the groove by the casing preventing rotation of the piston stem and thereby the piston relative to the casing. In each of the mechanisms illustrated in Figs. 1 and 6 the lug 20 projects downwardly from the under side of the piston rod and in the mechanism illustrated in Fig. 4 35 it projects upwardly from the upper sidev of the piston rod.

In the form of the invention shown in Figs. 1 to 3, the upper side of the piston rod ll is provided with teeth 22 which mesh with the teeth 23 of a rockable pinion segment 24 preferably integrally connected to one end of a sleeve 25 rockably mounted on a pin 25 which extends at right angles to the piston rod and which is carried by the casing section 2. T0 the other end of 45 the sleeve 25 there is integrally connected a pinion segment 2i having teeth 28 which mesh with teeth 29 provided on one side of a vertically movable rack Sil which is slidably guided at its lower end by the casing section 2. The rack 3l) extends 50 above the sleeve 25 and pivotally mounted on the upper end of the rack by means of a pin 3i, is a pawl 32 which, as will hereinafter more fully appear, is adapted to be moved into and out of engagement with the teeth of the ratchet wheel I3.

The pawl 32 is provided with a laterally extending lug 33 which, when the rack 3B is in its lower or normal position as shown, is engaged by a stationary lug 34 carried by the casing section 2 and which by reason of such engagement is maintained out of engagement with the ratchet wheel against the action of a spring 35 which is carried by the rack 36 and which tends to urge the latch toward the ratchet wheel.V

Unwanted rotation oi the adjusting nut I2 is prevented by the action of a leaf spring 36 which is secured to the casing section 2 and which frictionally engages the teeth of the ratchet wheel I3.

At one side of the piston I6 there is a chamber 3l which is connected to a pipe 33 which leads to the brake cylinder of a fluid pressure brake equipment. While the brake cylinder is not shown it will be understood that the pipe 38 may be connected thereto in the usual well known manner, in which, with the brakes released, the pipe is open to the non-pressure side of the brake cylinder piston and consequently to the atmosphere, and in which, whe-n effecting an application of the brakes, the piston travel is excessive, due to wear of brake shoes or connected brake elements, the pipe is connected to the pressure side of the brake cylinder piston. At the other side of the piston I6 there is a chamber 39 which is connected to the atmosphere through a passage@ in the casing section 2 or any other suitable atmospheric communication.

'I'he rack and pinion mechanism shown in Fig. 4 differs from that shown in Figs. 1 to 3 in that the pinions are arranged at the underside of the piston rod Il and on the right hand side of the vertically movable rack 30 and in that the rack 33 is located at the right hand side of the longitudinal axis of the adjusting nut I2. The slack adjuster shown in Fig. 6 diii'ers from that shown in Figs. 1 to 3 in that the actuating motor and rack and pinion mechanism are reversed end for end.

In operation, if in effecting an application of the brakes, the brake cylinder piston moves far enough to connect pipe 3B to the pressure side thereof, iluid under pressure will ilow through pipe 38 to piston chamber 3l of the slack adjuster. Fluid under pressure thus admitted to chamber 3l causes the piston I5 and thereby the piston rod Il to move inwardly compressing the spring i9. As the piston and piston rod thus move, the pinion segments are caused to operate to move the rack 3U upwardly. As the rack 33 is being moved upwardly the spring 35 acts to rock the pawl 32 into the path of travel of the teeth of the ratchet wheel I3, and as the movement of the rack continues, the pawl ratchets over the back of the iirst tooth beyond the end of the pawl and into operative engagement with said tooth when the piston rand thereby the rack have reached the limit of their travel.

When in eifecting the release of the brakes, the brake cylinder piston, in its movement to release position, again connects the pipe 33 to the nonpressure or atmospheric side of the piston, the pressure of huid in the take-up piston chamber 31 is reduced to atmospheric pressure.

As the pressure of fluid in chamber 3l is thus being reduced, the spring I9, which has been previously compressed, acts to move the piston rod il and thereby the piston I6 outwardly to their normal position as shown in the drawings. As the piston rod thus moves the pinion segments 2d and 2l are caused to rotate and move the rack 33 and thereby the pawl 32 downwardly. The pawl 32 being in engagement with a tooth of the ratchet wheel I3 will, due to its downward movement, rotate the adjusting nut I2 relative to the adjusting screw Ill, the nut causing the adjusting screw cross-head 'I and lever 9 to move toward the right to take-up slack. When the rack 30 nears its limit of travel, that is to say, when the piston I6 has nearly completed its outward stroke, the lug 33 of the pawl 32 is engaged by the stationary lug 34 on the casing section 2, so that as the movement of the rack 33 is continued, the pawl is caused to move out of engagement with the ratchet wheel I3, the actual separation of the pawl from the ratchet wheel occurring just shortly before the rack reaches its normal position in which it is shown in the drawings. The pawl 32 is now maintained in this position until such time as the piston Iii is again moved to effect the operation of theseveral parts of the adjuster to takeup slack.

With the pawl in its normal position as shown, the nut I2 may be rotated manually to reset the adjuster without opposition by the pawl.

In each of the forms of the invention shown the piston rod is so constructed that the pitch line of the teeth 22 at a point midway of the width of the faces of the teeth, is coincident with the longitudinal axisr of the piston. This arrangement eliminates the tendency of the piston and piston rod tol tilt as it is being moved by either iiuid pressure or spring pressure and further contributes to a more compact mechanism.

As shown the outer end of the adjusting nut I2 in each form of the invention is provided with a stop mechanism 45 which is for the purpose of facilitating the resetting of the adjuster when the adjusting screw I engages the mechanism and stops the pistonfl before the piston has completed its adjusting stroke, but since` this mechanism is substantially the same as that fully disclosed and broadly claimed in Patent No. 1,650,313 of Frederick G. Williamson, issued November 22, 1927, and since this mechanism is not claimed in the present application, further description thereof is deemed unnecessary.

While several illustrative embodiments of the vinvention have been described in detail, it is not rigging, in combination, a ratchet nut for taking up slack, a pawl operative to actuate said nut, a rack movable in the direction of its length for actuating said pawl, a pinion operative to actuate said rack, and means for actuating said pinion.

2. In an automatic slack adjuster forbrake rigging, in combination, a ratchet nut for taking up slack, a pawl operative to actuate said nut, a rack movable at an angle to the axis of said nut for actuating sai-d pawl, a pinion member operative to actuate said rack, a toothed member movable at an angle to the direction of movement of said rack for actuating said pinion member, and means for actuating said toothed member.

3. In an automatic slack adjuster for brake rigging, in combination, a ratchet nut for taking upn slack, a pawl operative to actuate said nut, a rack movable at an angle to the axis of said nut for actuating said pavvl, a pinion member operative to actuate said rack, a toothed member movable at an angle to the direction oi movement of said rack for actuating said pinion member, and means for actuating sai-d toothed member, the pitch line of the teeth of said toothed member being coincident with the longitudinal axis of said means.

4. In an automatic slack adjuster for brake rigging, in combination, a ratchet nut for taking up slack, a pawl operative to actuate said nut, a rack movable vertically for actuating said pavvl, a pinion member operative to actuate said rack, a toothed member movable along a line parallel with the longitudinal axis of said nut and at right angles to the line of travel of said rack for actuating said pinion member, and means for actuating said toothed member.

5. In an automatic slack adjuster for brake rigging, in combination, a casing, a ratchet nut for taking up slack, a pawl operative to actuate said nut, a rack operatively connected to said pawl, a pinion member carried by said casing operative to move said rack to actuate said pavvl, and means carried by said casing and movable at right angles to the longitudinal axis of said pinion member and to the line of travel of said rack for actuating said pinion member.

6. In an automatic slack adjuster for brake rigging, in combination, a casing, a ratchet nut for taking up slack, a rack slidably mounted in the casing for longitudinal movement, a pavvl carried by said rack and operative thereby to actuate said nut, pinion means carried by said casing and operable to actuate said rack, a toothed member slidably mounted in the casing and operative to actuate said pinion means and means for actuating said toothed member.

'7. In an automatic slack adjuster for brake rigging, in combination, a casing, a nut mounted in said casing operative to take-up slack, a rack slidably mounted in the casing for reciprocatory movement along a line at an angle to the axis of said nut, a pawl carried by said rack and operative thereby for actuating said nut, said pavvl being adapted to operatively engage said nut Without actuating it upon movement of the rack in one direction and being adapted to actuate the nut to take-up slack upon movement of the rack in the opposite direction, pinion means for moving said rack, and means for actuating said pinion means.

8. In an automatic slack adjuster for brake rigging, in combination, a casing, a nut mounted in said casing operative to take-up slack, a rack slidably mounted in the casing for reciprocatory movement along a line at an angle to the axis of said nut, a pawl carried by said rack and operative thereby for actuating said nut, said pawl being adapted to operatively engage said nut without actuating it upon movement of the rack in one direction and being adapted to actuate the nut to take-up slack upon movement of the rack in the opposite direction, means on said pavvl adapted to cooperate with said casing for automatically moving the paWl out of operative engagement with said nut at substantially the same time as said rack completes its slack takeup stroke, a pinion for moving said rack and means for actuating said pinion.

9. In an automatic slack adjuster for brake rigging, in combination, a casing, a nut mounted in said casing operative to take-up slack, a rack slidably mounted in the casing for reciprocatory movement along a line at an angle to the axis of said nut, a pawl carried by said rack and operative thereby for actuating said nut, said paWl being adapted to operatively engage said nut without actuating it upon movement of the rack in one direction and being adapted to actuate the nut to take-up slack upon movement of the rack in the opposite direction, a pinion member operative to actuate said rack, and a motor operated rack for actuating said pinion member.

FRANCIS E. SCHWENTLER, 

